The invention relates generally to methods and associated apparatus for controllably delivering radioactive or cytotoxic fluids for medical application, and specifically to methods and associated apparatus for the infusion of radioactive fluids for medical application, such as a liquid containing a radioisotope or biologically active substance.
In many medical applications it is necessary or desirable to administer amounts of radioactive fluids or medicines and other pharmaceutical fluids to a patient""s body. For example, I-131 is administered to a patient in need of radiotherapy or I-125 for diagnostics. Other medicines that may be administered include radiosensitizers, chemotherapy, biologically active substances, and cytotoxics.
Certain of these applications involve infusing the fluid directly into a patient, such as through an intravenous tube or through direct application of the fluid to a specific portion of the patient""s anatomy needing treatment or being subject to diagnostic procedures. Other medical applications involve infusing the fluid to a medical device located within or in proximity to the patient. An example of this type of application is illustrated in Williams U.S. Pat. No. 5,611,767. Williams shows an implantable balloon that can be filled with radioactive, chemotherapeutic or other fluids for treatment of marginal cancerous tissue remaining after surgical resection of a cancerous tumor. As further illustrated in Williams, fluids may be infused into the device, for example, by hypodermic syringe (FIG. 4 of U.S. Pat. No. 5,611,767) or by a transdermal catheter (FIG. 8 of U.S. Pat. No. 5,611,767). Even where a transdermal catheter is used, a hypodermic syringe is typically used to infuse the required fluid through the catheter.
Particularly in the case of radioactive fluid syringe injections, current methods of syringe shielding may not provide the patient or the medical practitioner with the total protection needed in terms of radiation shielding or containment of a spill or leak of the infusion system apparatus. Radioactive fluids are typically supplied to a balloon such as those illustrated in Williams, for a specified period of time. The fluid is then removed from the balloon and the balloon can be flushed with saline or some other nonhazardous dilutant before further surgery to remove the balloon from the patient""s body. The infusion, removal and flushing of the radioactive fluid results in the use of several syringes which must be interchanged in the infusion system with a resulting increase in the possibility that radioactive fluids will leak or spill.
Syringe shields are currently available and are generally made to shield a syringe filled with radioactive fluids by employing lead (Pb) as a means of shielding the radioactivity. These devices, however, generally protect patients and medical personnel only from radioactive fluids within the body of the syringe, but do not provide adequate shielding and containment of possible leaks or spills of the infusion system.
The invention provides an infuser for transferring hazardous treatment fluids to and from a medical application while protecting both patients and healthcare providers from potentially dangerous spills and leaks. The infuser includes a spill containing housing having a medical application connecting element and a syringe seat. The syringe seat of the infuser leads to a syringe connecting element that provides a fluid coupling between the syringe and a fluid passage leading to the medical application connecting element. The interior of the housing can be sealed against leaks, for example, by providing the housing in two portions with a gasket provided between the portions. A fluid tight coupling can be formed between the syringe and the interior of the housing by integrally forming a septum with the gasket, and coupling the syringe with the syringe connecting element through the septum. The infuser can thus transfer hazardous fluids from one or more syringes to a medical application with little or no risk of leaks or spills.
The infuser of the invention can also be provided with two syringe seats so that two different fluids can be transferred. This configuration is particularly useful where the hazardous fluid must be diluted or flushed. In one embodiment, a second syringe connecting element is provided in fluid-tight communication with a second fluid passage. The second fluid passage may connect to the first fluid passage in proximity to the first syringe connecting element, allowing fluid from the second syringe to flush out both fluid passages.
The infuser of the invention may also be shielded against radiation to prevent harm to patients and healthcare providers from radioactive materials within the infuser, whether within the fluid passages or generally within the sealed housing. The housing may also be provided with a fluid absorbing material to further control any leaked or spilled fluids within the housing. In addition, a unidirectional valve can be placed in the second fluid passage to prevent hazardous fluids from backing up from the first fluid passage to an unshielded syringe at the second syringe seat.
The invention also includes a method for transferring hazardous fluids to a medical application using an infuser of the invention having two syringe seats. The method involves placing a first syringe containing a therapeutic fluid in fluid communication with the first syringe connecting element; delivering a dosage of the therapeutic fluid to the medical application; placing a second syringe containing a filling fluid in fluid communication with the second syringe connecting element; and delivering an amount of filling fluid to the medical application. The method can include removing the therapeutic fluid from the medical application as well.